The present invention relates to stators for electrical motors and, more particularly, to a stator lamination design. Electric motors include a stator core which typically is made of a stack of thin, plate-like metal laminations. Such laminations typically are round, and have a central opening. Consequently, a stator core made up of a stack of such laminations is generally cylindrical in shape and includes a hollow, central cavity extending longitudinally about the central axis of the core.
The inner periphery of the core includes longitudinally-extending slots shaped to receive insulated conductors or windings, which may be wires or rods wound with fabric or fiberglass tape, that receive electric current that creates electric fields in the stator core. Such slots are formed in the stator core by stamping notches about the inner and outer peripheries of each lamination, and then stacking the laminations such that the notches in the laminations are aligned. Windings are retained in the core slots by flat strips of heavy cardboard which fit into cutouts formed in the profiles of the notches. Such cutouts are positioned radially outside of the windings in the notches.
U.S. Pat. No. 4,704,787 to Herzog et al. discloses a process for producing a core winding which shows a stator lamination having coil slots. An insulating plastic is provided between the stator winding rods and a wedge of insulating material is provided in a notch over the windings in order to seal the slot and retain the windings within the slot. A disadvantage of such conventional stator lamination shapes is that the slot profiles of the laminations have sharp corners located where the notch meets the outer periphery of the lamination, and where the cutouts meet the side wall of the notch. During conductor insertion and removal, the insulation can get "hung up" on these sharp corners and the sharp corners can cut into the insulation, ultimately exposing the conductor. Once the conductor is so exposed, the conductor must be repaired or replaced to avoid a short circuit.
Accordingly, there is a need for a stator lamination design which minimizes the likelihood of damage to the insulation covering the conductors sustained during insertion of the conductor into the core slot and removal of the conductor from the core slot.